MAMMAL DEMENTIA: HABs, CTE and the lost sea lion

This 10-year-old male sea lion swam, waddled, and crawled more than 50 miles from the ocean. Like football players suffering from CTE, the sea lion was suspected of suffering from disorientation, dementia and other mental disorders. Photo credit Ken Shively.

By Scott A. Rowan

The mysterious case of the sea lion crawling into the cattle field miles from the ocean is one of the most recent and bizarre examples of the negative domino effect in nature due to global warming and human interference, according to experts.

While the cause of the sea lion’s unprecedented journey is still being investigated, it is only one anecdote in what will become a laundry list of Mother Nature oddities if the suspected cause is proven to be what scientist’s suspect.

On April 15, cattle farmer Ken Shively returned home to discover that the gate to his pen of cows was crashed open on his organic farm in Oakville, Washington. Lying on the ground nearby was the immediate suspect: an immobile brown lump of an animal that weighed hundreds of pounds and was apparently dead. Expecting to find a dead deer or elk, Shively approached the animal and was stunned when it turned its head and began to bark at him.

The farmer immediately ran into the house and asked his wife about the sea lion in the driveway.

“She thought I was pulling her leg,” Shively told The (Tacoma) News Tribune.

Shively’s phone call to the Department of Fish and Wildlife was met with the same incredulous response at first.

“They didn’t believe us,” Shively said. “They were like, ‘A what? Can you describe that to us?’ They didn’t even know where Oakville was.”

When officials from the department arrived on the scene, the three law officials and marine mammal biologist Dyanna Lambourn realized Shively’s call was no prank. There, in the driveway, 50 miles from the ocean, was a living male sea lion, all 350 pounds of him.

“After 16 years, this is the most unusual [call] I’ve had,” Sgt. Bob Weaver said. “It was an unusual sight to see.”

Humans weren’t the only ones perplexed by the unprecedented visitor.

“All our cows came running over to see what all the excitement was about,” Shively said.

Sea lions are known to swim up rivers in pursuit of salmon and fish, but the closest thing to a river near Shively’s farm is the Garrad Creek, which is so shallow in parts that the water level is only about a foot. Rumors of a sea lion living in Garrad Creek had circulated through the small community for about a month, so Shively was not surprised by the visitor, but not as stunned as might be expected.

The most logical explanation biologists and law enforcement officials could determine was that the sea lion managed to swim, waddle and crawl approximately five miles up the Garrad Creek, then transferred to a local drainage ditch and used the ditches and road to make his way to the Soggy Bottom Farm, where he barged through the gate after a passing car or something else spooked him.

Officials guide the lost sea lion found on the Soggy Bottom Farm into a cage. Credit: Ken Shively.

SAD END
Lambourn examined the sea lion on the scene and determined that the 10-year-old mammal was thin and underweight, but otherwise healthy and with no obvious physical trauma. The biologist estimated the sea lion’s weight to be about 350 pounds, roughly half what an adult male sea lion should weight.

Without the facilities to rehabilitate the malnourished sea lion, Lambourn decided that the animal should be returned to the ocean immediately. Before releasing the sea lion into the Puget Sound near Solo Point, Lambourn applied a safe green paint to him normally used for cattle and sheep to help identify the wayward mammal in case of any future human interactions.

Lambourn and her assistants released the sea lion into the Puget Sound hours after receiving Shively’s call.

On April 21, witnesses saw a sea lion sunning itself near the Port of Olympia and reported that it looked healthy, but made no mention of seeing the identifying green paint. The following day, however, the body of a dead male sea lion was found nearby, on its side was Lambourn’s green paint.

On Apri 24, Lambourn performed the necropsy on the sea lion and was unable to determine the cause of death. However, suspecting a known poison in the water that affects all mammals, including humans, she sent samples for testing. While the results of the tests have yet to come back, many aquatic experts agree with Lambourn’s suspicion that domoic acid, a lethal neurotoxin created by algae blooms, is the most likely cause of death.

HABs and CTE

This deep red harmful algae, called Lingulodinium polyedrum, is a type of HAB that often produces brightly colored water discoloration. It has been associated with fish and shellfish mortality events, and its threat to human health is still being evaluated. Credit: Kai Schumann.

Football fans are becoming increasingly aware of the degenerative mental effects of consistent head trauma, leading to chronic traumatic encephalopathy (CTE). Though experts still need to study CTE more to understand it, the degenerative condition is believed to be the cause of death for many former professional football players.

Symptoms of CTE include memory loss, erratic behavior, impaired judgment, and dementia, according to the Brain Injury Research Institute.

Those are all the same symptoms that mammals exhibit after ingesting domoic acid, a neurotoxin that is becoming increasingly more common along shores. In sea lions, domoic acid can cause the animals to lose memory and the ability to navigate properly, as well as cause physical seizures and death.

Domoic acid is toxic to all animals in the food chain, not just large mammals. The government is forced to prohibit harvesting of mollusks and bivalves (clams, mussels, oysters, quahogs, etc.) as well as shellfish (crabs, lobsters, etc.) along shores where there are high levels of domoic acid because the poison has been attributed to more than 100 human deaths and many more cases of permanent brain damage.

THE TAKEAWAY

Warning signs like this one in Maine are posted in public areas have been contaminated with high levels of toxins in shellfish and other aquatic species. Credit: NOAA.

While domoic acid occurs naturally, it is becoming increasingly apparent and found more often than in the past, which isn’t good for mammals. Domoic acid is a byproduct harmful algae blooms (HABs) that becoming more common and “sinister,” according to the National Oceanic and Atmospheric Administration.

HABs occur naturally and can be found along every coastline in the United States. These HABs are a threat to human and animal alike because, in addition to creating domoic acid, HABs rob the ocean of oxygen, suffocating fish and other animals, and clog fish gills as well as smother coral and underwater vegetation.

NOAA and other aquatic agencies are rushing to learn more about HABs because these swarms of algae are not only lethal but occurring more frequently, which cripples both ocean-based economies and inhabitants of the ocean.

Though HABs occur naturally, particularly in the aftermath of hurricanes, drought, or floods, scientists are learning that manmade actions can exacerbate and even cause HABs. Chemical runoff from agricultural and lawn products into rivers, bays, and the ocean increase the levels of phosphorus, nitrogen and other nutrients in the water which “overfeeds” the algae, leading to HABs occurring in locations that would not otherwise happen and contributing to massive HABs that threaten the financial and health future of everyone – human and animal – living in or near the water.

NOAA estimates that HABs cost the United States approximately $82 million per year.

Of course, there are other costs from HABs, such as the life of a wayward sea lion who, confused and disoriented, wound up on a cattle ranch shortly before his premature death.

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